DESCRIPTION(Provided by applicant): The long-term goal of this research proposal is to understand the roles of the estrogen receptors, ERa\ and ERB, in mediating nongenomic actions of estrogen in the brain and the strategy is to study this in a neuronal cell line expressing either ERa or ERB. Clinical studies have reported the delay of Alzheimer?s disease and cognitive decline in postmenopausal women taking Estrogen Replacement Therapy, suggesting the importance of estrogen in neuronal survival. Pharmacological studies in vivo as well as primary cultures have demonstrated estrogen to be neuroprotective at physiological concentrations against a variety of neurotoxic insults. Unexpectedly, estrogen neuroprotection has been demonstrated in the absence of protein synthesis and has been blocked by inhibiting rapid signaling, such as activation of mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (P13-kinase). Three specific aims seek to characterize the mechanism of rapid nongenomic actions of estrogen. Specific aim 1 will take a pharmacological approach to study the role of ERa and ERB in activating the intracellular signaling molecules, MAPK, P13-kinase, Ca2+ and cAMP using an ER-negative hippocampal-derived cell line that stably expresses ERa or ERB. Biochemical approaches will be used in specific aims 2 and 3 to determine whether ERa or ERB localize to the plasma membrane and more specifically to caveolae fractions where many of these signaling molecules reside. Estrogen plays an important role in neuroprotection and it is critical to characterize the mechanism of rapid signaling in order to understand how estrogen elicits neuroprotection.